Phospholipid-binding antibodies are heterogeneous immunoglobulins of G and/or M and/or A class which can be detected in association with a variety of pathologies. However they can also occur in the absence of any clinical manifestations. Despite their paradoxical in vitro anticoagulant activity, phospholipid-binding antibodies, either primary or secondary, are frequently associated with venous and/or arterial thrombotic events. Hence, their detection has to be performed in several major clinical situations, cerebral attack, myocardial infarction, recurrent fetal loss, deep vein thrombosis ... Their course has to be controlled at least every six months. Since the incidence of phospholipid-binding antibodies in auto-immune pathologies is high, immunological disorders should also be considered. As yet there is no standardized assay of phospholipid-binding antibodies, either functional with respect to their anticoagulant activity, or immunological (ELISA). It is not established whether they possess an own pathogenic potential or appear as a secondary response following cellular alterations known to be thrombogenic. However it has been suggested that they could participate in the disruption of the hemostatic balance towards procoagulant tendency resulting in thrombosis.